Imprint method, and imprint apparatus for implementing the same

ABSTRACT

An imprint method includes, in the peeling step of peeling a mold off the material layer to be transferred, a region-of-contact recognition operation of recognizing and determining a region of contact of the mold with the material layer to be transferred, a center-of-gravity locating operation of determining a center of gravity of a morphology of the thus recognized region of contact on the basis of that morphology, and a peeling operation of determining a point of force for applying peeling force to the mold or the imprinting substrate in relation to the center of gravity determined by the center-of-gravity locating operation, thereby acting the peeling force on the point of force.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imprint method and an imprintapparatus for transferring and forming a desired pattern (such as lines,and graphic patterns) on the material to be transferred.

2. Description of the Related Art

Attentions have now been focused on imprint methods that are a sort ofmicro-machining or micro-processing technologies. A typical imprintmethod is a pattern-formation technique that uses a mold member having aminute concavo-convex structure formed on a substrate surface totransfer that concavo-convex structure to the material to betransferred, thereby achieving full-size transfer of that concavo-convexstructure.

For such imprint methods, for instance, there has been a photo-imprintmethod or a thermal imprint method known in the art. In thephoto-imprint method, for instance, a photo-curing resin layer havingfluidity is located as the material to be transferred on a substratesurface, and a mold having the desired concavo-convex structure isengaged with that resin layer. In this state, the resin layer is thenirradiated with light from the mold or substrate side to cure the resin,after which the mold is peeled off the resin layer so that theconcavo-convex structure (concavo-convex pattern), where the concavitiesand convexities the mold has are inverted or flipped over, is formed onthe resin layer that is the material to be transferred. In the thermalimprint method, a thermoplastic or thermosetting resin is used insteadof the photo-curing resin. When the thermo-plastic resin is used, theresin is softened by heating into a fluid state, and the mold is thenengaged with the fluid resin to fill the resin up in the concavo-convexstructure on the mold, after which cooling is carried out to pull themold off the resin. For the thermosetting resin, heating is used as themeans for engaging the mold with it and curing the resin filled up inthe concavo-convex structure on the mold.

Thus, the imprint methods comprises the step of feeding the resinmaterial that is the material to be transferred to the substratesurface, the step of filling the resin up in the concavo-convexstructure on the mold, the step of curing the resin layer, and the stepof peeling the mold off the resin layer.

For the step of peeling the mold off the resin layer among these steps,there is a technique demanded that enables the mold to be impeccablypeeled off the resin layer while the morphology of the transferred resinconcavo-convex structure (concavo-convex pattern) is kept intact. Ingeneral, a risk of inconvenient deposition of the resin that is thematerial to be transferred onto the mold, and a risk of mold breakdownshas correlations with the peeling force necessary for peeling: it wouldappear to be that the stronger the peeling force, the heavier the risksof deposition and breakdowns are.

A method of forming a releasing layer containing a fluorine component orthe like on the concavo-convex surface of the mold has been proposed foruse with the technique for achieving the aforesaid impeccable peeling(for instance, see JP(A) 2007-326367). In order to reduce drasticfluctuations of surface area rates, there has also been a method putforward, in which a dummy template pattern is formed to prevent therelease rate from increasing drastically, thereby reducing theoccurrence of defects (for instance, see JP(A) 2010-225683).

However, although the method of providing the releasing layer on theconcavo-convex surface of the mold is very effective for where the areaof contact of the mold with the resin layer is limited, it is to beunderstood that when the area of contact grows large for the purposes ofboosted-up productivity or the like, the force necessary for peelinggrows much stronger, so the simple provision of the releasing layerwould be far away from the solution of a problem with peeling. Further,the prior art does not teach anything specific about any possible methodthat enables peeling with much less peeling force so as to avoid theoccurrence of inconvenient deposition onto the mold of the resin that isthe material to be transferred.

The aforesaid method of forming the dummy template pattern would also befar away satisfactory because even a portion of the pattern inessentialin itself is transferred to the degree that such a peeling pattern hasan adverse influence on later steps.

Having been accomplished with such situations in mind, the presentinvention has for its object to provide an imprint method that includesa specific peeling means that enables peeling with much less peelingforce depending on the morphology of the material or material layer tobe transferred thereby avoiding the occurrence of inconvenientdeposition onto the mold of the material or material layer to betransferred.

SUMMARY OF THE INVENTION

In order to accomplish such an object, the invention provides an imprintmethod, comprising a transfer material layer formation step ofinterposing the material or material layer to be transferred between asurface of a mold having an concavo-convex structure region and animprinting substrate to form a transfer material layer having aconcavo-convex structure pattern, and a peeling step of peeling saidmold off said material layer to be transferred, wherein:

said peeling step comprises a region-of-contact recognition operation ofrecognizing and determining a region of contact of said mold with saidmaterial layer to be transferred, a center-of-gravity locating operationof determining a center of gravity of a morphology of the thusrecognized region of contact on the basis of said morphology, and apeeling operation of determining a point of force for applying peelingforce to said mold or said imprinting substrate in relation to thecenter of gravity determined by said center-of-gravity locatingoperation, thereby acting the peeling force on the point of force.

In a preferable embodiment of the inventive imprint method, when thereis said center of gravity lying within the region of contact, at leastone point of force is located on a straight line including a linesegment having the greatest length with said center of gravity and anoutermost periphery of said region of contact as two ends.

In a preferable embodiment of the inventive imprint method, said pointof force is located outside an area of the outermost periphery of saidregion of contact.

In a preferable embodiment of the inventive imprint method, when thereis said center of gravity lying outside of said region of contact, anoperation of capturing sub-centers of gravity in a graphic pattern (or apattern) is implemented such that a morphology of the region of contactis divided into sub-regions so that the respective sub-centers ofgravity are included and set in the respective sub-regions, andthereafter, said point of force is located on a straight line includinga line segment having the greatest length with said sub-center ofgravity and an outermost periphery of the sub-region of contact as twoends.

In a preferable embodiment of the inventive imprint method, thepoint-of-force locating operation is further implemented, and theobtained line segments are used as vectors with the sub-centers ofgravity as origins to find a sum of said vectors, and the thus summedvector is drawn with the center of gravity as an initial point so that apoint of force is set on an extension of that vector.

In a preferable embodiment of the inventive imprint method, in relationto the original center of gravity of the region of contact before beingdivided, said point of force is located at a position getting astride ofthe region of contact.

In a preferable embodiment of the inventive imprint method, when thepeeling operation is implemented with points of force located at aplurality of sites, force in a direction opposite to a peeling directionis temporarily applied to a site where an internal angle of the regionof contact exceeds 180° or a stress concentration site that is a sitewhose curvature takes on a negative value.

In a preferable embodiment of the inventive imprint method, the force ina direction opposite to a peeling direction is applied to a lowerelasticity modulus one of both the mold and the substrate.

The present invention also provides an imprint apparatus, comprising:

a mold holder for holding a mold in place,

a substrate holder for holding an imprinting substrate in place,

a region-of-contact measuring instrument for recognizing and determininga region of contact with said mold of the material or material layer tobe transferred that is interposed between a surface of the mold havingan concavo-convex structure region and the imprinting substrate, and

a data processing unit operable to execute computation and command tasksfor controlling a state of the mold being peeled off the material layerto be transferred, wherein:

said data processing unit comprises a center-of-gravity computationportion for determining a center of gravity of a region of contactrecognized by said region-of-contact measuring instrument, and apoint-of-force computation portion for determining a point of force forapplying peeling force to the mold or the imprinting substrate.

In a preferable embodiment of the inventive imprint apparatus, said moldholder or said substrate holder includes a peeler, wherein said peeleris operable to apply the peeling force to the point of force.

The inventive imprint method includes, and is comprised of, a resinlayer formation step of interposing a material or material layer to betransferred between a surface of a mold having a concavo-convexstructure region and an imprinting substrate to form the material layerto be transferred with a concavo-convex structure pattern, and a peelingstep of peeling said mold off the resin layer, wherein the peeling stepcomprises a region-of-contact recognition operation of recognizing anddetermining a region of contact of the mold with the material layer tobe transferred, a center-of-gravity locating operation of determining acenter of gravity of the morphology of the thus recognized region ofcontact on the basis of said morphology, and a peeling operation ofdetermining a point of force for applying peeling force to the mold orimprinting substrate on the basis of the determined center of gravity,thereby acting the peeling force on the point of force. The arrangementbeing like this, it is possible to implement peeling with much lesspeeling force depending on the morphology of the material or materiallayer to be transferred, thereby avoiding the occurrence of inconvenientdeposition onto the mold of the material or material layer to betransferred.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C are illustrative in schematic and section over timeof one example of the imprint method according to the invention.

FIGS. 2A, 2B, 2C and 2D are plan views for illustrating the positions ofthe centers of gravity for a variety of graphic patterns.

FIG. 3A is a plan view for illustrating how to set a point of peelingforce in the case where the center of gravity G of the region of contactlies within the region of contact, and FIG. 3B is a side view of FIG.3A.

FIGS. 4A to 4E are illustrative over time of how to determine the pointof force in the case where the center of gravity of the region ofcontact does not lie within the region of contact.

FIG. 5 is illustrative in perspective of an operation of temporarilyapplying a force P′ in a direction opposite to a peeling direction to astress concentration site where the internal angle of the region ofcontact exceeds 180 degrees.

FIG. 6 is a plan view of an L-shaped material, illustrating whether ornot the internal angle corresponds to a site exceeding 180°.

FIG. 7 is a plan view of a case where regions of contact do not cometogether, for instance, five regions of contact exist discretely.

FIG. 8 is a front view of one example of the imprint apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Some embodiments of the invention will now be explained.

The inventive imprint method includes, and is constructed of, a transfermaterial layer formation step of interposing the material to betransferred that is a to transfer material between a surface of a moldhaving a concavo-convex structure region and an imprinting substrate toform the material layer to be transferred with a concave-convexstructure pattern, and a peeling step of peeling the mold off thematerial layer to be transferred. The material to be transferred thatforms the material layer to be transferred here typically includesthermoplastic resins, and thermosetting resins in addition to theaforesaid photo-curing resins; however, it is noted that inorganicmaterials other than those resins may also be used. For instance,glasses such as quartz glass, soda lime glass and metal ion-containingglass are capable of being fluidized by heating. Further, mixtures ofinorganic and organic materials may be used too. Materials composedmainly of silsesquioxanes as an example may be regarded as thermosettingor photo-curing materials depending on the materials to be contained inthem, and silsesquioxane may just only be broken down into an inorganicmaterial because of having a Si—O—Si skeleton, but may also be used inmuch the same way as the aforesaid thermosetting resins because it iscapable of being fluidized and thermally set. If the silsesquioxane isallowed to contain photo-polymerizable groups such as oxetanyl or acrylgroups, on the other hand, it may have photo-curability, so it may beused as a photo-curing resin.

By way of example but not by way of limitation, the invention is nowexplained with reference to a resin material as a preferable example ofthe material to be transferred.

[Imprint Method]

First of all, the imprint method is explained in details with referenceto FIG. 1.

Among imprint methods known so far in the art, there are a photo-imprintmethod and a thermal imprint method. However, the photo-imprint methodis here explained as one of the imprint methods.

In the photo-imprint method, a photo-curing resin material 5 is fed andlocated on a surface 7 a of an imprinting substrate 7 as the material tobe transferred, as shown typically in FIG. 1A. Feeders for the resinmaterial 5 include a dispenser, an inkjet or the like. Although somedroplets of the resin material 5 are shown, it is to be understood thatthe number and location of droplets of the resin material 5 mayoptionally be determined. Alternatively, the photo-curing resin material5 may be formed as a uniform film on the surface 7 a of the substrate 7as by spin coating.

For instance, the imprinting substrate 7 may be constructed of glasseslike quartz glass, soda lime glass, and borosilicate glass;semiconductors like silicon, gallium-arsenide, and gallium nitride;resin substrates like polycarbonate, polypropylene, and polyethylene;and metallic substrates or, alternatively, a composite materialsubstrate comprising any combination of those materials. The substrate 7is not necessarily flat; so it may be have a predetermined structure.For instance, the substrate 7 may have on it any desired patternstructure such as a micro-wire used for semiconductors, displays or thelike, and an optical structure like a photonic crystal structure, alight guide, and a holographic structure. However, it is preferable thatthose structures do not stand in the way to transfer; that is, it ispreferable that they are located in such a way as not to interfere withthe morphology of the mold 1 and the concavo-convex structure the mold 1has, or care is taken of how to transfer as by filling material up inconcavities or recesses in the pattern structure to make it flat.

As shown in FIG. 1A, the mold 1 is located and provided opposite to theimprinting substrate 7. A surface 1 a of the mold 1 is constructed of aconcavo-convex structure region A1 having a concave structure comprisingconcavities 2 to be transferred, and a non-concavo-convex structureregion A2 where there is none of the concavo-convex structure to betransferred. Although the structure to be transferred is shown as beingconcave with respect to the non-concavo-convex structure region A2, itis to be understood that the structure to be transferred may be convexor both convex and concave.

The mold 1 may be formed of any desired material; however, when theresin material 5 is photo-curing, the mold 1 is formed of a substratetransparent to light for curing the resin material 5. For instance, usemay be made of glass like quartz glass, silicate glass, calciumfluoride, magnesium fluoride, and acryl glass, and resin likepolycarbonate, polypropylene, and polyethylene, or any laminatedmaterial of these. However, when the substrate 7 is transparent to lightfor curing the resin material 5, the mold 1 is not necessarily formed ofa transparent substrate; so use may be made of metals such as nickel,titanium, and aluminum, and semiconductors such as silicon, and galliumnitride. The mold 1 may have a thickness selected in consideration ofthe morphology of the concavo-convex structure, substrate strength, theability of handle or the like, for instance, from the range of about 300μm to 10 mm. The mold 1 may have a so-called mesa structure wherein thewhole of the concavo-convex structure region A1 is convex relative tothe non-concavo-convex structure region A2, and the mesa structure mayhave one or more steps.

Then, as shown in FIG. 1B, the surface 1 a of the mold 1 having thedesired concavo-convex structure is brought in contact with the resinmaterial 5 located in place, optionally with the application of pressure(the so-called mold forcing step). In this state, the resin material 5turns to a resin layer having a concavo-convex structure, and the resinmaterial 5 is cured by irradiation with ultraviolet radiation (theso-called resin curing step). Thereafter, the mold 1 is peeled off theresin material 5, as shown in FIG. 1C, whereby a resin layer 5′ havingan inverted concavo-convex structure of the concavo-convex structure themold 1 has is transferred onto the imprinting substrate 7.

Part of the invention lies in the peeling step of peeling the mold 1 offthe resin layer 5′ wherein a specific peeling method is used to enablethe mold 1 to be peeled off the transferred resin layer 5′ with muchless peeling force so that inconveniences such as deposition onto themold of the resin to be transferred, and mold breakdowns can be avoided.The peeling step that is part of the invention is now explained.

[Explanation of the Peeling Step that is Part of the Invention]

The peeling step of the invention includes the region of contactrecognition operation of recognizing and determining the region ofcontact of the mold with the resin layer, the center-of-gravity locatingoperation of determining the center of gravity of the morphology of therecognized region of contact of the resin layer on the basis of thatmorphology, and the peeling operation of determining the point of forcefor applying peeling force to the mold or imprinting substrate therebyapplying the peeling force to that point of force.

First of all, the region-of-contact recognition operation is explained.

[Region-Of-Contact Recognition Operation]

By implementing the region-of-contact recognition operation in thepeeling step, the morphology of the region of contact of the mold withthe resin layer is recognized. The “region of contact” here isunderstood to refer to an overall region where the mold having aconcavo-convex structure region pattern is in contact with the resinlayer.

Referring to an example of the region-of-contact is recognitionoperation, for instance, an actual region of contact may be measured assuch. That is, the region where the mold is actually in contact with theresin layer to be transferred is directly measured by aregion-of-contact measuring instrument. Although there are severalrecognition means or methods available, it is to be understood thatpreference is given to an optical measuring method. This may havecorrelations with the explanation of the apparatus to be describedlater, and it is here noteworthy that when the region-of-contactmeasuring instrument is used in combination with the optical method, themold should preferably be constructed of a material transparent toelectromagnetic waves for the reason of recognition by electromagneticwaves, and that a holder for that mold, a peeling device or the likeshould preferably be provided with an opening in the site necessary formeasurement in such a way as not to shield off electromagnetic waves orformed of a material that does not shield off electromagnetic waves. Forinstance, when infrared radiation is used as the electromagnetic waves,the holder or the like may be constructed of a material transparent toinfrared light such as silicon. When the electromagnetic waves used havea wavelength identical with or close to that of light for curing theresin, it is possible to implement the region-of-contact recognitionstep and the resin layer curing step at the same time so that the regionof contact can be recognized without any increase in the step count. Ifthe mold, the holder for the mold, the peelers or the like cut offelectromagnetic waves, it is preferable that the region-of-contactmeasuring instrument is located on the substrate side.

More specifically, the region-of-contact recognition method usingelectromagnetic waves should preferably rely upon A: image capturing,and B: edge detection by light scattering as mentioned below.

A: Image Capturing

For instance, a CCD camera, lenses or the like are used as theregion-of-contact measuring instrument to capture images of a portionwhere the mold is actually in contact with the resin layer to betransferred. Image resolution is dependent on the performance of opticalparts such as lenses, and the number of pixels of the CCD, so it mayoptionally be selected depending on the precision of the end capturedinformation, and so on. When the image resolution is affected bycontrasts, it may be optimized by taking care of how to illuminate. Noparticular limitation is imposed on the light source and CCD camera, ifthey are capable of recognition of the region of contact. For the lightsource, use may be made of the one that is capable of giving out lightto which shields such as the mold and holder are transparent, andpermits the CCD camera to receive that light.

B: Edge Detection by Light Scattering

Use may also be made of the method that uses edge detection by lightscattering to detect the contour (or outer edge) of a portion where themold is in contact with the resin layer to be transferred.

For instance, a plane including a region of contact wherein the mold isin contact with the resin layer to be transferred is defined as the X-Ycoordinate. Laser light operable as the region of contact measuringinstrument is used to scan that region of contact plural times in theX-axis direction, for instance, while it is gradually shifted at minutepitches in the Y-axis direction. As a matter of course, the Y-axisdirection scanning may be implemented instead of the X-axis directionscanning. If the light at this time is detected, it is possible torecognize the contour of the portion of contact where the mold is incontact with the resin layer to be transferred. To put it another way,changes in the state of light scattering or reflection, and changes inthe state of light transmission are detected with respect to the edgethat is the contour of that portion of contact. By way of example butnot by way of limitation, the light emitting portion, and the lightreceiving portion may be located at a position where such changes aredetectable.

Image resolution is contingent on scan pitches; so the scan pitch mayoptionally be selected such that the given resolution is obtainable.Laser spot size has an influence on resolution too; so the laser spotsize may optionally be selected such that the given resolution isobtainable. For edge detection, it is preferable that there aredistinctions in the reflection or transmission state; so influences ofrefractive index, reflectivity, and transmittance should preferably betaken into consideration too.

The prerequisite for both the aforesaid measuring methods is that inorder to transmit the electromagnetic waves used for measurement fromthe region-of-contact measuring instrument to the mold to the resinlayer to be transferred, there is an opening provided in the mold holderto keep open the upper portions of the mold and the resin layer to betransferred, or the mold holder and so on are constructed of a materialthat does not shield off electromagnetic waves. However, the inventionis not limited to these; there may be a detection method C used:detection by sound waves (shock or impulse waves) that is capable ofdetecting the region of contact with no need for the formation ofopenings or the like, as mentioned below.

C: Detection by Sound Waves (Shock or Impulse Waves)

With shock waves that are an element for forming the region-of-contactmeasuring instrument, the contour of the portion of contact of the moldwith the resin layer to be transferred can be recognized using theirreflection off a discontinuous substance surface.

For instance, suppose now that from an ultrasonic generator (not shown)closely located nearly all over the upper surface of the mold 1 in thestate depicted in FIG. 1B, ultrasonic waves are being generated from theupper surface of the mold 1 down toward the resin layer to betransferred (downward in the drawing sheet). Then, ultrasonic waves willbe reflected off the discontinuous substance portion. In short, there isa difference in reflection intensity depending on whether a site wherethere is the resin layer on the lower surface of the mold 1 or a sitewhere there is an air layer devoid of the resin layer. By detecting thisdifference, the contour of the region of contact is determined. Herenote that if sound wave losses are negligible, it is not necessary tobring the ultrasonic generator and its associated detector in closecontact with the mold or the resin layer to be transferred. Forinstance, they may be located indirectly with a fluid like water betweenthem.

Preferably, the region-of-contact recognition operation using theaforesaid region-of-contact measuring instrument should be implementedevery time pattern transfer is carried out; however, there is anexception. For instance, when the region of contact of the mold with thematerial to be transferred would always be expected to be uniform, theregion-of-contact recognition operation may possibly be omitted, giventhe expected region. Also, when imprinting is implemented under the sameconditions, it may be not necessary to apply the aforesaidregion-of-contact recognition operation to all imprinting cycles. Inthis case, it is unnecessary to implement the region-of-contactrecognition operation for each imprinting. Those cases implicate, ratherthan that the region-of-contact recognition operation does not takeplace for each imprinting, that the results of the region of contactrecognition operation implemented once or several times during aplurality of imprinting cycles may have been applied to every otherimprinting, and the region-of-contact recognition operation may havebeen implemented in the peeling step. Of course, even when imprinting isconducted plural times, the region-of-contact recognition operation maybe left out if the region of contact of the mold with the material to betransferred could be expected in advance.

Once the region-of-contact recognition operation for recognizing anddetermining the morphology of the region of contact of the mold with theresin layer has been implemented as described above, thecenter-of-gravity locating operation is carried out to determine thecenter of gravity of the morphology of the region of contact of the moldwith the resin layer on the basis of that morphology. Thecenter-of-gravity locating operation is now explained.

[Center-of-Gravity Locating Operation]

The center-of-gravity locating operation is now set forth with referenceto some specific examples of how to determine the center of gravity.

In the invention, how to determine the center of gravity is of vitalimportance because how to determine the point of force is based oncorrelations with the center of gravity. In geometric parlance, thecenter of gravity is defined the way that “when the region of contact isviewed as a single graphic pattern (or a pattern), the center of gravityis described as the point where linear moment around that graphicpattern is zero”. Generally for the determination of the center ofgravity on the basis of such a definition, multiple integral isemployed. When the density of the graphic pattern is regarded as beinguniform, there is also a method using the exterior product of vectors.These calculation methods here are not expounded because of beinggenerally well-known mathematical conception.

Therefore, there are some methods exemplified below that enable thecenter of gravity to be more easily figured out. These methods make itrelatively easy to use the results of the already mentionedregion-of-contact recognition operation; so they offer practicallypreferred method examples.

1. Method Approximating to a General Graphic Pattern

In this method, the results of measurement of the morphology of theregion of contact are compared with simple graphic patterns for whichhow to determine the center of gravity is generalized, and the mostapproximate one is picked. For instance, the method is carried outaccording to the following order (a), (b) and (c).

-   -   (a) Information about the region of contact is captured in. The        results of the aforesaid region-of-contact recognition operation        are employed.    -   (b) The most approximate graphic pattern is selected from the        data base.    -   (c) The center of gravity of the selected graphic pattern is        determined according to the definition.

Specifically, when it comes to the polygon shown in FIG. 2A, there isthe center of gravity G at equal distances from the respective apexes.When it comes to a circle, there is the center of gravity at its center,and when it comes to the ellipse depicted in FIG. 2B, there is thecenter of gravity G at the point of intersection of the major and minoraxes. When it comes to the parallelogram depicted in FIG. 2C, there isthe center of gravity G at the point of intersection of diagonal lines.When it comes to the deformed quadrilateral depicted in FIG. 2D, thecenters of gravity A₁ and A₂ of two triangles bisected by a diagonalline A, and the centers of gravity B₁ and B₂ of two triangles bisectedby a diagonal line B are determined so that the center of gravity G ofthat deformed quadrilateral is determined by the point of intersection Gof a straight line that connect A₁ and A₂ and a straight line thatconnect B₁ and B₂.

2. Polygon Approximation 1: Method for Determining the Center of Gravityfrom the Coordinates

When a plane including the region of contact of the mold with the resinlayer to be transferred is expressed in terms of the X-Y coordinateswith any arbitrary point defined as the origin, there is a methodavailable wherein there are the coordinates obtained for the peripheralportion of the region of contact, and the center of gravity isdetermined by making approximation to a polygon having the obtainedcoordinate data as apexes. This method is applicable to wherecoordinates (X₁, Y₁), (X₂, Y₂), . . . (X_(i), Y_(i)), . . . (X_(n),Y_(n)) for the peripheral portions of the region of contact areobtained. Consider now that the periphery of the region of contact isrepresented by connecting these coordinates by line segments inadjoining order, and suppose that S is the area of the polygon obtainedby connecting the coordinates by straight lines. Then, the center ofgravity (X₉, Y₉) is given by the following equations.

X _(g)=(1/6S)Σ(X _(i) ÷X _(i+1))(Y _(i) X _(i+1) −X _(i) Y _(i+1))

Y _(g)=(1/6S)Σ(Y _(i) +Y _(i+1))(X _(i) Y _(i+1) −Y _(i) X _(i+1))

where S is the area of the polygon created by connecting the coordinateswith straight lines.3. Polygon Approximation 2: Method for Determining the Center of Gravityfrom the Area of a Unit Graphic Pattern

When a plane including the region of contact of the mold with the resinlayer to be transferred is expressed in terms of the X-Y coordinateswith any arbitrary point defined as the origin, there is a methodavailable wherein the region of contact is considered as being anapproximate of a set of graphic patterns, each one having a certainarea. For instance, suppose now that n squares, each one having acertain area A, are spread all over the region of contact, and thegraphic pattern has an area S (=nA). Then, the center of gravity (X_(g),Y_(g)) is given by the following equations.

X _(g)=(1/S)ΣAX _(i)

Y _(g)=(1/S)ΣAY _(i)

[Method of Determining the Point of Force where Peeling Force is Appliedto the Mold or the Imprinting Substrate]

In the invention, the determination of the point of force where peelingforce is applied to the mold or the imprinting substrate (thedetermination of the position where force acts) is made on the basis ofcorrelations with the aforesaid center of gravity of the region ofcontact.

It is to be noted that the determination of the point of force varies interms of how to deal with between cases where there is the center ofgravity inside and outside the region of contact, so it is now explainedwith reference to two such cases.

(How to Determine the Point of Force when the Center of Gravity Lieswithin the Region of Contact)

FIG. 3A is a plan view for the illustration of how to set the point ofpeeling force where the center of gravity G of the region of contactlies within the region of contact, and FIG. 3B is a side view of FIG.3A.

Referring to FIG. 3A, a mold 1 is constructed of a transparent materialas an example, so that a resin layer 5′ can be viewed directly throughthe mold 1. A region indicated by A1 in FIG. 3A, and FIG. 3B is aconcavo-convex structure region of the mold provided with concavities(the portion where there is a so-called graphic pattern).

As depicted in FIG. 3A, when there is the center of gravity G of theregion of contact (here synonymous to the center of gravity G of theresin layer 5′) within the region of contact, at least one point ofpeeling force according to the invention is located on a line segmenthaving the greatest length with the center of gravity G and theoutermost periphery F of the region of contact (here synonymous to theouter frame shape F of the resin layer 5′) as two ends, viz., a straightline L including a line segment GQ in the morphology shown in FIG. 3A.

In order to implement efficient peeling, it is particularly desired thatthe point of peeling force is set outside the outermost periphery F areaof the region of contact. In the example depicted in FIG. 3A, the pointof force P is determined further outside the point Q of the line segmentGQ, and peeling (upward) force is applied to that point of force P. Ifpeeling takes place first through the line segment GQ having thegreatest length, it is then possible to concentrate the force on onepoint on the outermost periphery of the region of contact, pulling thetrigger of peeling with small force but with ease and for sure. Althoughthe peeling force is shown as being applied to the mold 1 side, it is tobe understood that the peeling (downward) force may be applied to theimprinting substrate 7 side or both the mold 1 and the imprintingsubstrate 7 instead.

Pursuant to the aforesaid law, there may be two or more points of forceset. In the example depicted in FIG. 3A, for instance, another point offorce P2 may be set on the straight line L including the line segment GQand in a direction opposite to the point of force P. However, it is tobe noted that when the peeling force is applied to two points of force:P and P2 with the region of contact interposed between them, there is arisk that excessive stress may act on a single point of the resin 5′ atthe end of the peeling operation, because the site, at which the peelingoperation gets completed, lies halfway the region of contact. When thesite, to which excessive stress is applied, matches with the portion A1having the pattern, there is a possibility of doing damage to thepattern. It is thus preferable that stress is controlled such that thesite, at which the peeling operation gets completed, is off the portionA1 having the pattern. When there is no option but to allow the peelingoperation to get completed at the portion A1 having the pattern, it ispreferable that well managed stress control is implemented such that thenecessary and minimum stress is applied at the end of the peelingoperation.

Although it is preferable that the point of force is set as far from thecenter of gravity as possible for the efficient application of force,yet it would also be necessary to take into account how to retain theapparatus, mold shape, substrate shape, etc.

Referring back to FIG. 2 with reference to which the position of thecenter of gravity G is explained, a supplemental explanation is providedof a variation of how to determine the point of force for theapplication of peeling force. With such a regular octagon as depicted inFIG. 2A, there are four straight lines L on which the point of force maybe set: one at the minimum and eight at the maximum. Given eightstraight lines lying on the straight line L and extending outwardly ofthe region of contact, the “maximum number” here is understood to referto the number of points of force in the case where a single point offorce is provided per one straight line. In other words, when two ormore points of force are provided per one straight line, the maximumnumber varies correspondingly. Generally given a regular N-gon, there isa variation in the number of straight lines L on which the points offorce may be set depending on whether N is an even or odd number. When Nis an even number, the number of straight lines L on which the points offorce may be set becomes N/2, and when N is an odd number, the number ofstraight lines L on which the points of force may be set becomes N.

With such an ellipse as shown in FIG. 2B, the major axis matches with aline segment on the straight line L with the point of force set on itand within the region of contact. One point of force is provided at theminimum, and two at the maximum. With such a parallelogram as depictedin FIG. 2C, the longer of the orthogonal lines matches with a linesegment of the straight line L with the point of force set on it andwithin the region of contact. One point of force may be provided at theminimum, and two at the maximum.

How to determine the point of force when there is no center of gravityfound within the region of contact is now explained.

(How to Determine the Point of Force when there is No Center of GravityFound within the Region of Contact)How to determine the point of force when there is no center of gravityfound within the region of contact is explained with reference to FIG.4.

When, as shown in FIG. 4A as an example, the center of gravity G liesoutside of the region of contact (e.g., the resin layer 5′), there arethe following operations (a), (b) and (c) implemented, whereby theregion of contact is divided into sub-regions; the respectivesub-centers of gravity are included in the respective sub-regions(operation of capturing the sub-centers of gravity in the graphicpattern); and the respective sub-centers of gravity are set in therespective sub-regions.

First of all, as shown in FIG. 48, (a) a line segment h is drawn withthe center of gravity G and the periphery of the area of the region ofcontact 5′ as two ends. More specifically, the drawing operation isimplemented such that the area ratio of sub-regions of contact 51 and 55bisected by the line segment h is substantially 1, i.e., the region ofcontact 5′ is bisected by the line segment passing through the center ofgravity G into two sub-regions of contact 51 and 55. The “substantially1” here is understood to mean that when the areas of the sub-regions ofcontact 51 and 55 are indicated by A51 and A55, the value of[(A51−A55)/A51]×100 falls within the range of ±10%. When the number ofsub-regions of contact is greater than 2, the aforesaid value figuredout of the maximum and minimum area values of each sub-region of contactmay fall within the range of ±10%. The number of divisions mayoptionally be set for the reasons to be given later.

Then, as shown in FIG. 4C, (b) an operation is implemented torecalculate the centers of gravity of the sub-patterns (the sub-centersof gravity) for the respective two sub-regions of contact 51 and 55,thereby determining the sub-center of gravity G1 of the sub-region ofcontact 51 and the sub-center of gravity G2 of the sub-region of contact55. In the example of FIG. 4C, the sub-centers of gravity are alreadyincluded in the region of contact at this point in time; in other words,the operations (a) and (b) get completed. When the sub-centers ofgravity are not yet included in the sub-regions of contact in oneoperation, however, the operations (a) and (b) are repeated as anoperation (c) until the sub-centers of gravity are included in thesub-regions of contact.

As described previously, however, there may also be an option ofarbitrarily setting the number of divisions in the first divisionoperation without recourse to such a repetitive division operation,thereby dispensing with the operation for re-dividing the sub-patterns.The method of setting the number of divisions in the first place has amerit of equivalently dealing with the state of contact with the moldall over the divisions, because the sub-regions of contact havesubstantially equal areas as a consequence.

By contrast, the method of repeating bisection has a merit of obtainingthe minimum number of centers of gravity. As described previously, thesub-centers of gravity G1 and G2 are included in the respectivesub-regions of contact 51 and 55. Thereafter, as shown in FIG. 4D, apoint of force may be set on a straight line L1 including line segmentsG1-K1 and G1-M having the greatest length with the sub-center of gravityG1 and the outermost periphery F1 of the sub-region of contact 51 as twoends. It is here to be noted that the less the centers of gravity, theless the process loads on the calculation of the point of force becomes.Although the graphic patterns drawn in a set of FIG. 4 inclusive of FIG.4D are not precise, FIG. 4D is drawn as a graphic pattern wherein theline segment L1 passes through K1 and G1, and the line segment G1-K1 isequal to the line segment G1-M. Indeed, however, another force of pointmay be set on an extension from the line segment G1-M, too, although notillustrated.

Again, there may be a point of force set on a straight line L2 includingline segments G2-K2 and G2-M having the greatest length with thesub-center of gravity G2 and the outermost periphery F2 of thesub-region of contact 55 as two ends. Although the graphic patternsdrawn in a set of FIG. 4 inclusive of FIG. 4D are not precise, FIG. 4Dis drawn as a graphic pattern wherein the line segment L2 passes throughK2 and G2, and the line segment G2-K2 is equal to the line segment G2-M.Indeed, however, another force of point may be set on an extension fromthe line segment G2-K, too, although not illustrated.

In the embodiment depicted in FIG. 4D, there are two points of force P1and P2 set. More specifically, one point of force P1 is set on thestraight line L1 and at a site outwardly of point K2, and another P2 isset on the straight line L2 and at a site outwardly from point K2. Onlyone of the points of force P1 and P2 may be used or, alternatively, theremaining one may be sorted out, as mentioned above.

Although how to divide the graphic pattern has so far been explained, itis to be understood that there are some other methods, by which the sameresults as shown in FIGS. 4A, 4B and 4C are obtained. For instance, whenthe region of contact is taken as being a polygon, suppose that theregion of contact is approximated as a graphic pattern wherein somepolygons have a side sharing. Then, a simpler method may be used todetermine the center of gravity of each polygon.

The specification of setting the point of force shown in FIG. 4D may befurther extended to a more preferable one for setting the point of forceas shown in FIG. 4E.

According to the specification of setting the point of force as shown inFIG. 4E, there are vectors obtained with the sub-centers of gravity ofthe obtained line segments G1-M and G2-M as the origins. Suppose nowthat the initial points of the vectors are the centers of gravity G1 andG2, and the terminal point is M that is the periphery of the region ofcontact. Then, the sum of the vectors is found. When the thus obtainedvector is drawn with the center of gravity G of a graphic pattern(matches with the original pattern in FIG. 4) as the initial point,which graphic pattern is obtained by combining together the patternshaving the centers of gravity G1 and G2, respectively, a point P_(G) asan example may be set as a point of force on an extension of thatvector. It is preferable that the point of force P_(G) thus lying at onesingle site is located in a certain relation to the center of gravity Gof the original region of contact before division, i.e., in such a wayas to get astride of the region of contact.

Next, the state of peeling where the peeling force is being applied totwo points of force P1 and P2 depicted in FIG. 4D is compared with thestate of peeling where the peeling force is being applied to the pointof force P_(G) depicted in FIG. 4E.

In the former state of peeling wherein the peeling force is beingapplied to two points of force P1 and P2 (see FIG. 4D), as forces P1 andP2 are applied as depicted in FIG. 5, portions of the resin layergradually peeled off the two sites direct from A toward B, and from Ctoward B. The then inside bending line ABC provides a site whosecurvature takes on a negative value near point B. The “curvature” hereis a reciprocal of the radius of curvature, indicating the ratio atwhich the tangent vector of the pattern is bending. That this value isnegative indicates that when force applied from outside the region ofcontact is applied to the periphery of the region of contact, the forcecomponent matches with a site inward of the region of contact, and when,as shown in FIG. 5, forces acting from two directions are not uniformand there is torsion in the force acting on the periphery of the regionof contact, excessive peeling stress is added to near the point B,resulting in possible breakdowns in the material being peeled in one ormultiple points of the periphery of the region of contact where thepoints A, B and C link together. To avoid this, it is preferable toimplement an operation of temporarily applying force P′ in the directionopposite to the peeling direction to a site where the curvature of theregion of contact takes on a negative value, as depicted in FIG. 5. Inthis case, the opposite force P′ may be plural in number. This may inturn enable the resin layers being slowly peeled off in both peelingdirections to merge together timely at the stress concentration site orpoint B. At the point of timely confluence, the opposite force P′ isremoved, and peeling keeps going on. When the peeling force acts on twopoints of force P1 and P2, therefore, breakdowns in the resin layer atthe site of confluence are highly unlikely.

The opposite force P′ may be applied to one or both of the mold and thesubstrate, because it is applied for the purpose of the timelyconfluence of the resin layers at the stress concentration site or pointB. However, when the side having a higher elasticity modulus has muchdifficulty following the side that has a lower elasticity modulus and sodistorts more upon receiving the same stress, the opposite force P′should preferably be applied to the lower-modulus member of both moldand substrate members. Where peeling goes toward completion, it ispreferable to gradually decrease the opposite force P′.

This phenomenon could again happen even with a polygon. Referring toFIG. 6, there is a site at an apex D, where the internal angle of theregion of contact exceeds 180°, and as shown in FIG. 5, this sitematches with a stress concentration site where the force componentapplied from outside the region of contact directs to the inside of theregion of contact. In short, the site to which the opposite force P′ isto be applied may here be defined by a site whose curvature takes on anegative value or whose internal angle exceeds 180°.

Regardless whether the region of contact is a polygon or a curved line,or it is composed of an angle and a curved line, it is desired to findout the stress concentration site. Although this may be achievable invarious ways, there is the simplest way to determine the stressconcentration site by looking for a site of intersection of the regionof contact and a tangent line drawn at any arbitrary point on theperiphery of the region of contact. For instance, referring to aneasy-to-understand example of FIG. 6 illustrative of an L-shaped resinlayer, a line 1 that does not intersect the region of contact may bedrawn at a position of point E (with an internal angle θ1) (which doesnot correspond to a site having an internal angle of greater than 180°),but a line that does not intersect the region of contact cannot be drawnat a position of point D (with an internal angle θ2) (which correspondsto a site having an internal angle of greater than 180°).

On the other hand, the latter specification for setting the point offorce P_(G) shown in FIG. 4E does not offer such a problem with theaforesaid specification for setting the point of force shown in FIG. 4D,dispensing with the operation of adding the opposite force P′ that maybe rather a surplus one. Thus, the specification for setting the pointof force P_(G) shown in FIG. 4E provides the optimum point of force forthe application of the peeling force.

(How to Determine the Point of Force when there are Independent,Discrete Regions of Contact)

How to determine the point of force when there is one region of contacthas been described above. When there are five discrete regions ofcontact as shown in FIG. 7 as an example (five regions of contact areshown as graphic patterns 1 to 5) where they do not come together, thatis, when a plurality of graphic patterns are included in a singleone-shot mold, it is preferable to determine the point of force asfollows.

-   (1) The precedence of the graphic patterns to be peeled off is    determined. That is, the precedence of the pattern to be peeled off    impeccably is determined.-   (2) The center of gravity is figured out for each pattern to find a    point-of-force candidate.-   (3) It is preferable that the following operation is implemented    with the obtained point-of-force candidates for the center of    gravity to single out the optimum point of force. That is:    -   Points of force lying in regions unselected for the reason of        the apparatus per se are excluded from the obtained        point-of-force candidates to single out a selectable point of        force.    -   Common features to the respective patterns are found, and the        most frequently found common feature is defined as the point of        force to which the largest force is to be applied.    -   When there are some candidates under the same conditions, a        certain one is temporarily selected or, alternatively,        precedence is given in advance to the patterns to pick one        having higher priority.        However, the aforesaid method is given for the purpose of        illustration alone, so the present invention is not limited        thereto.

[Explanation of the Imprint Apparatus]

One preferable example of the inventive imprint apparatus is shown inFIG. 8.

An imprint apparatus indicated generally by 10 includes a mold holder 11operable to hold a mold 1 in place, a substrate holder 17 operable tohold an imprinting substrate 7 in place, a region-of-contact measuringinstrument 30 operable to measure the region of contact with the mold 1of a resin layer 5′ to be transferred that is interposed between themold 1 and the imprinting substrate 7, and a data processing unit 100operable to execute primary tasks, say, computation and commands forcontrolling the state of the mold 1 being peeled off the resin layer 5′.

As described previously, the region-of-contact measuring instrument 30may be constructed of, for instance, an image capturing device having aCCD camera, lenses or the like, a device capable of edge detection bylight scattering, and a device capable of detection by sound (or shock)waves. Particular preference is given to an optical measuring methodbecause of simplicity. With the region-of-contact measuring instrumentmaking use of an optical measuring method, however, it is to be notedthat for the reason that recognition is implemented with electromagneticwaves, the mold should preferably be formed of a light-transmittingmaterial, and mold peelers 21 and 22, the mold holder or the like shouldpreferably be provided with an opening 90 at the site necessary formeasurement such that they do not cut off electromagnetic waves, asshown in FIG. 8. Of course, there is an exception where if the area tobe irradiated with measuring electromagnetic waves for measurement ismade of a material that does not shield off electromagnetic waves, suchopening 90 may be dispensed with.

The data processing unit 100 includes a first computation block 103having a center-of-gravity calculator for figuring out the center ofgravity of the region of contact of the resin layer 5′ recognized by theregion-of-contact measuring instrument 30, and a second computationblock 104 having a point-of-force calculator for determining the pointof force for applying peeling force to the mold 1 or the imprintingsubstrate 7. Although the first 103 and the second computation block 104are exemplified as being separate from each other for the purpose ofillustration alone, it is to be understood that they may be combinedinto one single computation block.

The center-of-gravity locating operation at the center-of-gravitycalculator for determining the center of gravity of the region ofcontact may be implemented, using an integral method, a method using theouter product of vectors, a method using an approximation to generalgraphic patterns, a method using a polygonal approximation pluscoordinates, a method using an polygonal approximation plus unit patternarea or the like, as already described. At the point-of-force calculatorfor determining the point of force for the application of peeling force,calculation, settings and so on take place along the aforesaidpoint-of-force determination method depending on whether there is thecenter of gravity within the region of contact or there is none of thecenter of gravity within the region of contact.

As shown in FIG. 8, the peripheral edge of the plane (backside) of themold holder 11 opposite to the side having the mold 1 held in place isprovided with peelers 21 and 22, each built up of, for instance, anactuator, a spring and so on. For the reasons of space, only two peelers21 and 22 are shown; however, it is usually desired that more peelersare provided almost all over the backside peripheral edge of the moldholder 11 so as to make the point-of-force setting area as wide aspossible. If there can be the point-of-force setting area provided at alimited place alone, it is then possible to vary the holding positionsof the mold and/or the substrate before peeling so that the force can beapplied to the determined point of force. Such peelers 21 and 22 areoperatively joined to a first stress measuring instrument 40 and astress control unit 60, respectively. Upon peeling, the stress controlunit 60 is operable to control the force applied to a given point offorce determined by the peeling method of the invention, and the firststress measuring instrument 40 is operable to actually measure the forceapplied to the peelers 21 and 22 as well. It is here to be noted thatthe stress control unit 60 is also operatively joined to the pressurizer80 to be described later to enable forces applied for just only peelingbut also pressurization to be controlled as well; however, it may beprovided independently for pressurization and peeling.

As shown at the lower portion of the drawing sheet of FIG. 8, thesubstrate holder 17 operable to hold the imprinting substrate 7 in placeis operatively joined to the pressurizer 80. The pressurizer 80 isprovided for the application of force opposite to the peeling operation,and built up of an actuator and springs, for instance. In the embodimenthere, the force opposite to the peeling operation may be applied to anyarbitrary site of the imprinting substrate 7 via the substrate holder17. The pressurizer 80 is also operatively joined to the stress controlunit 60 and a second stress measuring instrument 70, respectively. Thestress control unit 60 is operable to control the pressurizing force(the force opposite to the peeling operation) produced out of thepressurizer 80, and the second stress measuring instrument 70 isoperable to measure the force acting on the pressurizer uponpressurization. Such stress control unit 60 and such second stressmeasuring instrument 70 are operatively joined to the data processingunit 100 for the implementation of data processing, control,measurement, and so on.

In the embodiment here, the data processing unit 100 includes an inputblock 101 for receiving data from the respective measuring instruments30, 40 and 70 and information from an input device 110, an recognitionblock 102 operable to recognize the outermost periphery area of theregion of contact for data processing, a first computation block 103operable to determine, for instance, the center of gravity of the regionof contact from the outermost periphery area, and the state of stressacting on the peelers and puressurizer, a second computation block 104operable to determine, for instance, the position of the point of forcewith respect to the center of gravity, and the stress to be applied tothe peelers and puressurizer, a verification block 105 operable toverify whether or not there are errors in the respective operationswithin the data processing unit, an output block 106 operable to issuecommands to the peelers and pressurizer, and send information out to anexternal output, and an internal memory block 107 operable to built upinput data or obtained data.

Such data processing unit 100 is operatively connected to externaldevices such as input device 110, output device 111, and external memorydevice 112. The input device 110, for instance, is operable to enterdata and commands in the data processing unit from outside. Given theinput device 110, the point of force determined by another device may besent out to the data processing unit 100 from the input device as thecase may be, or information about the region of contact may be enteredfrom the input device 110 into the data processing unit 100.

The output device 111, for instance, is operable to produce informationout of the data processing unit, and the external memory device 112 isan external one operable to build up input data and obtained data, as isthe case with the internal memory device.

Although one embodiment of the preferred imprint apparatus is shown inFIG. 8, it is to be understood that the inventive apparatus may bemodified in various forms without being limited thereto. Although thepeelers 21 and 22 are shown as being mounted on the mold 1 side as anexample, it is understood that they may be mounted on the imprintingsubstrate 7 side or, alternatively, they may be mounted on both sides.Although the pressurizer 80 is shown as being mounted on the imprintingsubstrate 7 side as an example, it is to be understood that it may bemounted on the mold 1 side or, alternatively, it may be mounted on bothsides. The peelers 21, 22 and the pressurizer 80 may be mounted on thesame mold 1 side or the same imprinting substrate 7 side. The peelers21, 22 may be integral with the molder holder 11. Likewise, thesubstrate holder 17 may be integral with the pressurizer 80.

Although the region-of-contact measuring instrument 30 is shown as beingmounted on the mold 1 side, it is to be noted that it may be mounted onthe substrate 7 side. The respective blocks in the data processing unitare operable to figure out both the region of contact and stress;however, they may separately be figured out.

There is an exception where if the region of contact of the mold withthe material to be transferred is expected to be always uniform, thepredetermined morphology of contact may have been entered in the dataprocessing unit 100. In this case, the region-of-contact measuringinstrument 30 is not always necessary. If the region-of-contactmeasuring instrument 30 is used, it can then be used as a tool forchecking whether or not there is proper contact, or for the purpose ofmorphological recognition for correcting deviations from thepredetermined morphology. These functional features may be mounted onthe first computation block 103 or the recognition block 102.

Such entering of information in the data processing unit from outsidecould be highly probable. In short, the imprint apparatus shown in FIG.8 is described such that every operation from the measurement of theregion of contact to peeling is enabling. However, when it comes only tothe case where the region of contact of the mold with the material to betransferred is expected to be always uniform, it is not always necessaryfor the recognition block 102, first computation block 103, secondcomputation block 104 and verification block 105 to be built in the dataprocessing unit 100; the results of calculation of the center of gravityand the point of force implemented outside of the apparatus may be givenfrom the input device 110 to the data processing unit 100. In this case,the apparatus used for the external calculation of the center of gravityand the point of force may be taken as a part of the inventive imprintapparatus.

The inventive imprint apparatus includes a resin material feedermechanism, although not shown. As shown in FIG. 1A as an example, thisfeeder mechanism is operable to feed a resin material 5 onto theimprinting substrate 7. Inkjet equipment may be exemplified as oneexample of the resin material feeder mechanism. Optionally, the feedermechanism may be provided with photo-curing or thermal setting means forcuring the resin material, and cooling means (used typically for athermoplastic resin).

Although the mechanism for bringing the mold in contact with thesubstrate is not drawn in the apparatus drawing, it may be providedseparately from or integrally with the peeling mechanism.

EXAMPLE

The present invention is now explained in further details with referenceto a more specific example.

Example 1

A region of contact (resin layer 5′) similar to such morphologies asdepicted in FIGS. 3A and 38 was prepared. Unlike FIG. 3A, however, theregion of contact is of morphology capable of approximating to arectangle. Suppose now that the teardrop in FIG. 3A takes on arectangular morphology.

Quartz glass having a surface size of 40×40 mm and a thickness of 6.35mm was used to prepare a mold. A pattern depth of 50 nm and a linewidth/space of 50 nm/50 nm were repeated 100 times into a length of 2mm. Four such patterns were provided, one at the center of the mold, andthree 5 mm away from the center in the XY direction. In short, theconcavo-convex structure region A1 may be taken as a rectangle of 10.02mm×14 mm at the center of the mold surface.

The mold surface was coated with a releasing agent Optool DSX (DaikinIndustries, Ltd.).

A silicon substrate of 0.625 mm in thickness was provided as animprinting substrate.

A photo-curing resin material having the following composition was addeddrop-wise to an area of 23×33 mm larger than the concavo-convexstructure region A1 at a pitch of 0.5 mm such that a rectangular resinlayer morphology was obtained on a portion of the surface of theimprinting substrate corresponding to the concavo-convex structurepattern of the mold, using inkjet equipment.

(Composition of the Photo-Curing Resin Material)

Isobornyl acrylate: 38% by weightEthylene glycol diacrylate: 20% by weightButyl acrylate: 38% by weight2-Hydroxy-2-methyl-1-phenyl-propan-1-one: 2% by weight2-Perfluorodecylethyl acrylate: 1% by weightMethyl perfluorooctanolate: 1% by weight

The mold having the concavo-convex structure pattern was allowed to drawnear to the imprinting substrate to which the resin material was fed asdescribed above. There was here a gap of 15 μm set between the mold at anon-concavo-convex structure region (at a site where there was none ofthe concavo-convex structure) and the imprinting substrate.

In that state, the mold side was irradiated with parallel light from thelighting optical system of the imprint apparatus (ultraviolet radiationhaving a peak wavelength of 365 nm) under the condition of 100 mJ/cm²,whereby the photo-curing resin material was cured into a resin layer(the resin layer formation step of forming a resin layer having theconcavo-convex structure pattern). The resin layer was obtained in arectangular morphology.

Then, the peeling step was implemented to peel the mold off the resinlayer as follows.

The region-of-contact recognition operation was implemented to recognizeand determine the region of contact of the mold with the resin layer,using a CCD camera. Then, the center-of-gravity locating operation wasimplemented to determine the center of gravity of the morphology of thethus recognized region of contact based on that morphology.Consequently, the region of contact was found to have a size of 25 mm×35mm, a morphology taken as being substantially equal to a rectangle, sothat the center of gravity could be determined by a method of findingthe point of intersection of the orthogonal lines of the rectangle.

Then, in conjunction with the center of gravity determined by thecenter-of-gravity locating operation, the point of force for peelingaccording to the invention was determined. That is, the point of force Pwas determined on a straight line including a line segment having thegreatest length with the center of gravity G and the outermost peripheryof the region of contact as two ends, and outside of the region ofcontact having that line segment.

The peeling operation was implemented by applying peeling (upward) forceto the point of force P with the result that stress at the initial pointof peeling could be reduced down to as small as 16.8N. It was thus foundthat 36.2N—the stress required for the conventional operation ofapplying uniform peeling force to the mold or the substrate in thevertical direction—can be reduced almost by half at the initial point ofpeeling according to the invention.

Thus, with the inventive imprint method including, in the step ofpeeling the mold off the material layer to be transferred, aregion-of-contact recognition operation of recognizing and determiningthe region of contact of the mold with the material layer to betransferred, a center-of-gravity locating operation of determining thecenter of gravity of the morphology of the thus recognized region ofcontact on the basis of that morphology, and a peeling operation ofdetermining the point of force for applying peeling force to the mold orthe imprinting substrate on the basis of the thus determined center ofgravity, thereby acting the peeling force on the point of force, peelingcan be implemented with smaller peeling force, resulting in avoidance ofinconveniences such as deposition onto the mold of the material to betransferred, i.e., the material layer to be transferred.

Especially in the invention, stresses at the initial point of peelingcan be reduced by determining the positional relation of the center ofgravity to the point of force. With the inventive peeling method, i.e.,with peeling implemented on the basis of how to determine the point offorce according to the invention, local stress can be applied to theboundary between the mold and the outer periphery of the material layerto be transferred. In addition, that stress can be applied withefficiency. The force to the region of contact concentrates primarily onthe outermost periphery of the region of contact via propagation.According to the invention, however, that force can be localized on asingle point on that outermost periphery so that the trigger of peelingcan be pulled with small force yet with ease and for sure. Once peelinghas been set off, the stress propagates over the surface of the contactof the mold with the material layer to be transferred.

Given how to determine the point of force according to the invention,the material layer to be transferred is less susceptible of tearingforce during the process of peeling, because as the force propagatesover the surface of contact, the resin is less susceptible of “torsion”during peeling. This in turn makes it easy to prevent the material to betransferred from getting deposited onto the mold.

It is here to noted that the present invention may be applied to theindustry in the form of micro-machining or the like using nano-imprinttechniques.

All the embodiments described so far herein are provided by way ofexemplification but not by way of limitation; so the invention may becarried out in a variety of other modified and altered embodiments.Therefore, the scope of the present invention should be defined by whatis claimed is and its equivalents.

1. An imprint method, comprising a transfer material layer formationstep of interposing a material or material layer to be transferredbetween a surface of a mold having an concavo-convex structure regionand an imprinting substrate to form a transfer material layer having aconcavo-convex structure pattern, and a peeling step of peeling saidmold off said material layer to be transferred, wherein: said peelingstep comprises a region-of-contact recognition operation of recognizingand determining a region of contact of said mold with said materiallayer to be transferred, a center-of-gravity locating operation ofdetermining a center of gravity of a morphology of the thus recognizedregion of contact on the basis of said morphology, and a peelingoperation of determining a point of force for applying peeling force tosaid mold or said imprinting substrate in relation to the center ofgravity determined by said center-of-gravity locating operation, therebyacting the peeling force on said point of force.
 2. A imprint method asrecited in claim 1, wherein when there is said center of gravity lyingwithin the region of contact, at least one point of force is located ona straight line including a line segment having the greatest length withsaid center of gravity and an outermost periphery of said region ofcontact as two ends.
 3. An imprint method as recited in claim 2, whereinsaid point of force is located outside of an area of the outermostperiphery of said region of contact.
 4. An imprint method as recited inclaim 1, wherein when there is said center of gravity lying outside ofsaid region of contact, an operation of capturing sub-centers of gravityin a graphic pattern is implemented such that a morphology of the regionof contact is divided into sub-regions, so that the respectivesub-centers of gravity are included and set in the respectivesub-regions, and thereafter, said point of force is located on astraight line including a line segment having the greatest length withsaid sub-center of gravity and an outermost periphery of the sub-regionof contact as two ends.
 5. An imprint method as recited in claim 4,wherein the point-of-force locating operation is further implemented,and the obtained line segments are used as vectors with the sub-centersof gravity as origins to find a sum of said vectors, and the thus summedvector is drawn with the center of gravity as an initial point so that apoint of force is set on an extension of that vector.
 6. An imprintmethod as recited in claim 5, wherein in relation to the original centerof gravity of the region of contact before being divided, said point offorce is located at a position getting astride of the region of contact.7. An imprint method as recited in claim 4, wherein when the peelingoperation is implemented with points of force located at a plurality ofsites, force in a direction opposite to a peeling direction istemporarily applied to a site where an internal angle of the region ofcontact exceeds 180° or a stress concentration site that is a site whosecurvature takes on a negative value.
 8. An imprint method as recited inclaim 7, wherein said force in a direction opposite to a peelingdirection is applied to a lower elasticity modulus one of both the moldand the substrate.
 9. An imprint apparatus, comprising: a mold holderfor holding a mold in place, a substrate holder for holding animprinting substrate in place, a region-of-contact measuring instrumentfor recognizing and determining a region of contact with said mold of amaterial or material layer to be transferred that is interposed betweena surface of the mold having an concavo-convex structure region and theimprinting substrate, and a data processing unit operable to executecomputation and command tasks for controlling a state of the mold beingpeeled off the material layer to be transferred, wherein: said dataprocessing unit comprises a center-of-gravity computation portion fordetermining a center of gravity of a region of contact recognized bysaid region-of-contact measuring instrument, and a point-of-forcecomputation portion for determining a point of force for applyingpeeling force to the mold or the imprinting substrate.
 10. An imprintapparatus as recited in claim 9, wherein said mold holder or saidsubstrate holder includes a peeler, wherein said peeler is operable toapply the peeling force to said point of force.